Linear tertiary amines with chain lengths between 8 and 24 carbon atoms are commonly referred to as fatty tertiary amines. According to Ullman's Encyclopedia of Chemical Technology, 5th edition, Volume A2, these materials, and their derivatives such as the corresponding quaternary ammonium compounds, are widely used in applications such as fabric softeners, drilling muds, surfactants, asphalt emulsifiers, and bactericides/disinfectants.
For fabric softeners, the most effective are the fatty quaternary ammonium compounds dialkyldimethyl ammonium chloride or the corresponding methyl sulfate. For drilling muds, methyl or benzyl quaternary ammonium chlorides produced from dialkyl methylamine are useful. For surfactants, C12 or C14 based alkyldimethylamine oxide is commonly used. For bactericides and disinfectants, alkyl(benzyl)dimethyl and alkyltrimethyl compounds in which the fatty alkyl group contains 12-14 carbon atoms are most effective against a broad range of organisms. Alternatively, the dialkyldimethyl compounds are most effective when the fatty alkyl group contains 8-10 carbon atoms.
Fatty amines are commonly produced from natural fats and oils or from conventional petrochemical raw materials. Three primary feedstocks are used to make fatty tertiary amines: fatty nitriles, fatty alcohols or aldehydes, and long chain olefins.
Fatty nitriles, which are formed from fatty acids and ammonia over dehydrating catalysts in liquid phase reactors or liquid and vapor-phase reactors at 280-360° C., are reacted either with dimethylamine or with formaldehyde and formic acid to produce N,N-dimethylalkylamines. See U.S. Pat. No. 4,248,801 to Lion Fat & Oil Co. and U.S. Pat. No. 3,444,205 to Hoechst.
Fatty alcohols and aldehydes can be converted into the same product via direct amination in the presence of dimethylamine or other primary or secondary amines at 160° C.-230° C. and low pressure (0.1-0.5 MPa) using copper chromite catalysts (for alcohol feedstocks) or noble metal, copper chelate, or copper carboxylate catalysts (for aldehydes). See U.S. Pat. No. 4,251,465 to Gulf Research and Development Co., U.S. Pat. No. 4,138,437 to Hoechst, and both U.S. Pat. No. 4,254,060 and 4,210,605 to Kao.
Long chain olefins are converted into the corresponding long chain amine products in the presence of dimethylamine or other primary or secondary amines via hydrobromination (with no added catalyst). See U.S. Pat. No. 3,471,562 and U.S. Pat. No. 3,497,555 to Millmaster Onyx, and U.S. Pat. No. 4,024,189 to Ethyl Corp.
These processes, however, produce a high content of terminal amines, typically 91 wt % or greater by weight of the amine. As used herein “terminal amines” means that the amine moiety is connected on the α or β carbon of the long chain alkyl chain of the amine.
For the case of amine oxide surfactants, this is done to provide good cleaning with high suds stability. However, sometimes it is desirable to produce with a high content (10 wt % or greater by weight of the amine) of internal amine. This would be useful for branched chain surfactants with improved cold water cleaning, moderate suds stability, and improved wetting properties.
Therefore, there is a need for a commercially feasible process for making long chain fatty tertiary amines and amine oxides which provide the desired content of internal amines, using hydrocarbons from a variety of sources. A secondary objective is to produce these amines via a low cost, economical process.